I don't think this would be the case but given the exact wording I'm not so sure. Technically speaking, as per the 4 page rules any models that aren't on the table are "held in reserve", so really summoning is more akin to Deep Strike in 40k (albeit triggered by magic) rather than creating new units, so I suppose you could say "hey this unit of blue saurus are part of the Sunclaw Star Host" and just not deploy them during set up, but then if you summon a yellow unit of Saurus then they wouldn't count as part of the Sunclaw host and not get the benefit.
I'd tread carefully though, I know a lot of people wouldn't be fond of this interpretation. As with most aspects of setting up an AoS game I'd say have a chat with your opponent first and see if you can come to an agreement with them.